Dual light-responsive shape transformations of a nanocomposite hydrogel sheet enabled by etching shaped plasmonic nanoparticles.

We report here on dual shape transformations of the same thermo-responsive hybrid hydrogel sheet under irradiation of a laser with two different wavelengths (808 nm and 450 nm). By etching the silver nanoprisms in the sheet to silver nanodiscs by using chloride ions (Cl), two areas with distinct light extinction properties are integrated in a single sheet. The conversion of photon energy to thermal energy in local areas by the silver nanoprisms or nanodiscs under laser irradiation with an appropriate wavelength heats up the sheet locally and causes a local volumetric shrinkage, and hence a volumetric mismatch in different areas in the sheet.